How can I check if <random piece of metal in house> provides ground?

[dfira]

So I happen to know my house is not grounded. My Landlord says this is fine, since it is protected by some other appropriate regulations.

I live on the 4th floor, and my terrace has a metal tap. Is there a test I can perform that will tell me if this tap provides ground or not?

My audio interface does emit a very small hum (around -58dB), is it true that if I run some conductive cable between the casing and the tap, should the hum disappear then I know I have found ground? Also, on the contrary, If it doesn't disappear, does that confirm it does not provide ground?

Thanks!

[Hugh Robjohns]

...is it true that...

No and no. Or at least, not necessarily. There are lots of possible causes for hum. I'd consult a qualified electrician to establish whether local regulations require exposed metalwork to be earthed, and whether or not it is!

[Eddy Deegan]

My Landlord says this is fine, since it is protected by some other appropriate regulations.

I'm not saying your landlord is misleading you but that's an assertion I would definitely double check with an independent professional.

[Wonks]

Can you confirm your country of residence? Some countries/electrical systems use the ‘TN-C’ method which ties neutral to ground, normally at the power cable entry to the building or the local transformer station, and relies on that and differential current circuit breakers for protection. Which is OK for general electrical safety but not good for audio purposes.

Different power systems described in the article below (showing 3-phase power but single phase domestic is otherwise identical, just without two of the phases).

https://www.emobilitysimplified.com/202 ... tt-it.html

[dfira]

Yeah I was umming an aahing about whether to out myself but yeah I'm in Spain, and i think in my city a lot of the older buildings just aren't grounded.

[The Red Bladder]

As Hugh states, it's no and no.

And yes, there are EU rules governing the earthing of buildings - they are supposed to be earthed and a good earth is vital to all things audio. Look out for "Application of equipotential bonding and earthing in buildings".

The UK rules are here - http://www.pts.ir/panel/images/post/kz1 ... 1-2015.pdf

A multimeter testing for continuity (i.e. a 0 ohm connection) between the tap and the earth wire would be a good start, but that just tests if the two are linked elsewhere and not to Mother Earth.

HOWEVER - most pipes in your building will be metal - usually copper, unless the water system was installed before 1970 or thereabouts, in which case they will be steel. The pipe coming into the building will probably be plastic and therefore of zero use as an earth. But those metal pipes within the building will be touching the brickwork all over the place and will certainly be better than nothing or a poke in the eye with a sharp stick. The pipe work should be connected with the house earthing wires anyway.

In the UK most pipes are copper, but our place in Germany got a whole new water system back in 1990 and that was totally PVC. Whether that trend reached Spain, I do not know!

Ideally, one drives an earthing spike into the ground outside and runs a thick earth wire to the house earth system.